Seventeen studies, with one reported as two separate studies (n=1,271,864 admissions: 580,776 control period and 691,088 intervention period) were included in the review. Two were RCTs, 12 before-and-after studies, two time series and two concurrent controls. Six studies were classed as high quality, two as fair and 10 as low quality.
Hospital mortality (15 studies): There was no significant difference in overall hospital mortality. There was evidence of significant statistical heterogeneity (I2=90.3%). Subgroup analyses indicated a significant reduction in hospital mortality in children (RR 0.79, 95% CI 0.63 to 0.98; four studies), but sensitivity analyses indicated that the pooled mortality estimate in children was not robust. There was no evidence of publication bias using the Begg test.
Cardiac arrest (16 studies): There was a significant overall reduction in the rate of cardiac arrest outside the intensive care unit (RR 0.65, 95% CI 0.55 to 0.77). There was evidence of significant statistical heterogeneity (I2=73.9%). Subgroup analyses reported a more modest reduction in cardiac arrest among high-quality studies of adult populations. Results from the sensitivity analyses were not reported. There was no evidence of publication bias.
The results of the cumulative influence of each study on the pooled mortality estimate in adults over calendar time showed that there was no association between lower hospital mortality and implementation of rapid response teams.